The arm rest housing is a recessed part provided approximately in the center of a seat back. The housing is generally formed by stitching of the cloth (b) which forms the upper wall to the cloths (a) and (a') which form the left and right side walls keeping the seams (c) and (c') outside, extending the extension of the cloth (b) around a frame (10) located inside the seat, fixing the end of such extension to a fixing wire (11) and affixing a panel (d) on the frame (10).
In the case of a conventional arm rest housing of this type, the cloth at the corners of the interior bulges which impairs the sense of beauty of the external appearance, and due to this bulging, the arm rest cannot be properly housed therein.